Matching Engine to Boat

FJK

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I have a 1968, 14' aluminum Starcraft Seafarer fishing boat. HP capacity per nameplate is 30. 15 inch transom. 1992, 9.9HP Johnson at 72 lbs. is a good match. Am considering a new 4 stroke but they all weigh more, around 100 lbs for same HP, more for electric start. How do I determine what engine weight is too heavy? Thank you.
 

tashasdaddy

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Re: Matching Engine to Boat

1968 33hp weighed 140 lbs. i assume this is a closed bow, with steering and remote controls, due to the 30 hp rating. for fishing a 9.9 will eventually get you there. i would put a new 25 2 stroke on it. they weight for hp to me in not worth it in a 4 stroke. also read making oil when trolling. http://forums.iboats.com/showthread.php?t=158085
 

CATransplant

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Re: Matching Engine to Boat

What TD said. Back in 1974, a 25 hp Johnson short shaft, rope start only weighed 85 lb. Light, huh?

I'd be aiming for something like that. The extra power would be great on those days when a storm blows in suddenly and you need to make a run for the dock.
 

mthieme

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Re: Matching Engine to Boat

My '78 35 weighs 150#, 2001 25 is 112#. These are both 2 cylinder Mercs. Electric start only adds 2-3 #, but this does not include the battery.
I've had 10 hp on 12' aluminum boats before and my brother had a 25 on a 12' AL before. If you're looking for something in the 100# range, you are not going to have any problems whatsoever.
You could get a 30 hp Yamato, they weigh in under 90#.:)
 

bowman316

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Re: Matching Engine to Boat

yea, my first thought is that a 9 hp is way under powered.

You want to be within 70% of the max hp rating, generally.
 

lakelover

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Re: Matching Engine to Boat

I have the same boat, albeit a 2003. Seafarer SF14S, rated for 30 hp. The hull weight is 225lb and I have an '03 Mercury 20 hp 2-stroke on it that weighs 114 lbs. It's a great combination but I wouldn't want any less hp on it. With just me, it will almost crack 30mph.

A very stable boat, and handles waves very well.

You can see it in my avatar.
 

FJK

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Re: Matching Engine to Boat

Thank you for the suggestions. It is an open bow, tiller steering, so the motor and I (180#) are in the stern. A 20HP Honda, short shaft, recoil start weighs 101 lbs. Don't really know if that's too much weight in the back end for proper handling. From your response, maybe it would be OK.
 

grego

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Re: Matching Engine to Boat

Lakelover, seems to have found a good comination, "old and new." I would go with what works for him and others.
 

rusirius

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Re: Matching Engine to Boat

Don't mean to threadjack here, but I saw this and completely lost it laughing and just had to share...

Why worry about weight?!?

My father and I were fishing on a local pond one time and saw two guys come by in their bass boat... It was 14-15' max and had a 150hp outboard on the back of the thing... I swear no exageration when they were sitting still the water level was only about 1" from the top of the transom...

"You boys better make sure you slow down REAL slow like..."

LOL!
 

grego

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Re: Matching Engine to Boat

Bass boats as a rule are compact even at 21 feet, they sit low in the water, allowing fish to be boated easyer. but they are very bouyant and fun to ride or watch at top speed throwing a thirty foot rooster tail!
 

lakelover

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Re: Matching Engine to Boat

Thank you for the suggestions. It is an open bow, tiller steering, so the motor and I (180#) are in the stern. A 20HP Honda, short shaft, recoil start weighs 101 lbs. Don't really know if that's too much weight in the back end for proper handling. From your response, maybe it would be OK.

I wouldn't think you'd have any problem at all with that combination, I bet you'd be very pleased. Total capacity on mine is listed as 920 lb.

Go for it! The guys in the picture are no lightweights...& it planes out nicely once it's opened up.

500-b879F.jpg
 

FJK

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Re: Matching Engine to Boat

Looks good in the picture with somebody in the center seat. I normally fish alone and wonder if you have trouble with what I believe is called porpoising when you are alone. With my 72# outboard, I put the 6 gal tank between the center and front seat to shift the weight to avoid this up and down pounding. Motor angle adjustment isn't always enough. Thank you.
 

lakelover

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Re: Matching Engine to Boat

Looks good in the picture with somebody in the center seat. I normally fish alone and wonder if you have trouble with what I believe is called porpoising when you are alone. With my 72# outboard, I put the 6 gal tank between the center and front seat to shift the weight to avoid this up and down pounding. Motor angle adjustment isn't always enough. Thank you.

No problem with that at all; I have the gas tank in front of the second seat (from the stern) and anchor in the bow. I usually ride alone too.

Motor trim is adjusted one hole from all the way out. I tried it trimmed all the way out and it was a little faster, but started to get squirrelly because the bow was up a little too high. I was afraid a gust of wind might cause some big problems, but it's fine one hole in.

In the photo above, they were going about half speed so I could get the picture from a slower boat as I went along side of them.
 

FJK

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Re: Matching Engine to Boat

Thanks for the info. One last question. That 20HP Merc is a short (15") shaft, right?
 

FJK

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Re: Matching Engine to Boat

Thank you Lakelover and all for suggestions. Have an enjoyable and safe boating season.
 

charles lates

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Mar 12, 2009
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Re: Matching Engine to Boat

I have a 1965 16' Starcraft Seafarer rated for 40hp. I recently went from a 1980's 15hp 2 stroke to a 2007 15hp 4 stroke which weighs about 115#. This setup works great and I often fish alone.
I did a search and saw that 2 stroke 40hp weigh about 150#, which is the weight of a typical 25hp 4 stroke, so my guess is that the weight on the transom is the defining factor not the max hp. You might want to check what 30hp 2 strokes weigh, I can't imagine that the amount would be greater than what a typical 20hp 4 stroke so you should be fine.
I can do about 14 mph alone (I weigh 230 ) with a cooler with 10# of ice and my fishing gear, which is plenty for me, so a 15 or 20hp on the 14' Seafarer should do that if not more.
 
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